Prophylactic antibiotic treatment in severe acute ischemic stroke: the Antimicrobial chemopRrophylaxis for Ischemic STrokE In MaceDonIa-Thrace Study (ARISTEIDIS)

New Directions in Infection-Associated Ischemic Stroke

The relationship between infections and stroke has not been fully characterized, probably delaying the development of specific treatments. This narrative review addresses mechanisms of stroke linked to infections, including hypercoagulability, endothelial dysfunction, vasculitis, and impaired thrombolysis. SARS-CoV-2, the virus that causes COVID-19, may promote the development of stroke, which may represent its most severe neurological complication. The development of specific therapies for infection-associated stroke remains a profound challenge. Perhaps the most important remaining issue is the distinction between infections that trigger a stroke versus infections that are truly incidental. This distinction likely requires the establishment of appropriate biomarkers, candidates of which are elevated levels of fibrin D-dimer and anticardiolipin/antiphospholipid antibodies. These candidate biomarkers might have potential use in identifying pathogenic infections preceding stroke, which is a precursor to establishing specific therapies for this syndrome.

Dysphagia after Stroke: An Unmet Antibiotic Stewardship Opportunity

The goal of antibiotic stewardship is to improve antibiotic use, often by reducing unnecessary treatment. Bedside dysphagia screening tools help identify patients at high risk of aspiration following stroke. Presence of dysphagia does not indicate a need for antibiotic treatment. Therefore, this retrospective, cohort study was developed to evaluate the association of dysphagia and antibiotic prescribing following stroke. There were 117 patients included. Patients were placed into 2 cohorts based on the results of the dysphagia screening, with 55 patients positive for dysphagia and 62 patients negative for dysphagia. Patients with dysphagia tended to be older, had higher National Institutes of Health stroke scores, and lower renal function. Patients with dysphagia were prescribed more empiric antibiotics than those without dysphagia (18.2% vs. 3.2%, p = 0.01). This resulted in 53 antibiotic days of therapy in the dysphagia cohort compared to 19 antibiotic days of therapy in the no dysphagia cohort (p = 0.1). No patients later developed pneumonia and only one patient was started antibiotics after 48 h. Two cases of Clostridioides difficile were reported. Both patients were in the dysphagia cohort and received antibiotics. Multivariable logistic regression demonstrated that positive chest x-ray findings and failed dysphagia screen were independent conditions associated with initiating antibiotics. These findings indicate that antibiotic use was higher in patients following stroke with a positive dysphagia screen. Close monitoring of stroke patients, particularly when positive for dysphagia, might be an under-recognized antibiotic stewardship opportunity.

Stroke Severity, and Not Cerebral Infarct Location, Increases the Risk of Infection

Infection is a leading cause of death in patients with stroke; however, the impact of cerebral infarct size or location on infectious outcome is unclear. To examine the effect of infarct size on post-stroke infection, we utilised the intraluminal middle-cerebral artery occlusion (MCAO) mouse model of ischemic stroke and adjusted the duration of arterial occlusion. At 1 day following stroke onset, the proportion of mice with infection was significantly greater in mice that had larger infarct sizes. Additionally, the presence of lung infection in these mice with severe strokes extended past 2 days, suggestive of long-term immune impairment. At the acute phase, our data demonstrated an inverse relationship between infarct volume and the number of circulating leukocytes, indicating the elevated risk of infection in more severe stroke is associated with reduced cellularity in peripheral blood, owing predominately to markedly decreased lymphocyte numbers. In addition, the stroke-induced reduction of lymphocyte-to-neutrophil ratio was also evident in the lung of all post-stroke animals. To investigate the effect of infarct location on post-stroke infection, we additionally performed a photothrombotic (PT) model of stroke and using an innovative systematic approach of analysis, we found the location of cerebral infarct does not impact on the susceptibility of post-stroke infection, confirming the greater role of infarct volume over infarct location in the susceptibility to infection. Our experimental findings were validated in a clinical setting and reinforced that stroke severity, and not infarct location, influences the risk of infection after stroke.

Preventive Antibiotics for Poststroke Infection in Patients With Acute Stroke: A Systematic Review and Meta-analysis

AIMS

To determine if preventive antibiotics is effective in poststroke infection in patients with acute stroke in comparison with no prophylaxis.

MATERIALS AND METHODS

MEDLINE (1950 to January 2017), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2017) and EMBASE (1974 to January 2017) databases were used to search for randomized controlled trials with intervening measures related to the preventive antibiotics in patients with acute stroke. Besides, the reference lists of the retrieved publications were manually searched to explore other relevant studies.

RESULTS

We included 6 randomized controlled trials involving 4110 stroke patients. The study population, study design, intervening measures, and definition of infection were different. Preventive antibiotics significantly reduced the incidence of algorithm-defined infection in patients with acute stroke from 11.14% (220/1975) to 7.43% (149/2006); odds ratio (OR)=0.41; 95% confidence interval (CI), 0.20-0.87; P=0.02. There was no difference in mortality between 2 groups, the mortality in preventive antibiotics group was 17.03% (347/2037) and control group was 16.10% (328/2037); OR=1.07; 95% CI, 0.90-1.27; P=0.44. And preventive antibiotics did not improve the proportion of good outcome, the proportion of good outcome in preventive antibiotics group was 45.47% (909/1999) and control group was 45.76% (913/1995); OR=0.89; 95% CI, 0.62-1.28; P=0.53. None of the studies reported severe adverse relevant to the study antibiotics.

CONCLUSIONS

Preventive antibiotics significantly reduced the incidence of algorithm-defined infection in patients with acute stroke, but did not decrease the mortality or improve the proportion of good outcome. Future research should aim to identify the group of stroke patients who will benefit most from antibiotic prophylaxis.

An insight into intestinal mucosal microbiota disruption after stroke

Recent work from our laboratory has provided evidence that indicates selective bacterial translocation from the host gut microbiota to peripheral tissues (i.e. lung) plays a key role in the development of post-stroke infections. Despite this, it is currently unknown whether mucosal bacteria that live on and interact closely with the host intestinal epithelium contribute in regulating bacterial translocation after stroke. Here, we found that the microbial communities within the mucosa of gastrointestinal tract (GIT) were significantly different between sham-operated and post-stroke mice at 24 h following surgery. The differences in microbiota composition were substantial in all sections of the GIT and were significant, even at the phylum level. The main characteristics of the stroke-induced shift in mucosal microbiota composition were an increased abundance of Akkermansia muciniphila and an excessive abundance of clostridial species. Furthermore, we analysed the predicted functional potential of the altered mucosal microbiota induced by stroke using PICRUSt and revealed significant increases in functions associated with infectious diseases, membrane transport and xenobiotic degradation. Our findings revealed stroke induces far-reaching and robust changes to the intestinal mucosal microbiota. A better understanding of the precise molecular events leading up to stroke-induced mucosal microbiota changes may represent novel therapy targets to improve patient outcomes.

Predictors of in-hospital mortality and dependence at discharge in patients with MCA stroke with intravenous thrombolysis

Early risk stratification of mortality and dependence is important for guiding medical decision-making in stroke care. The study aim is to evaluate whether there are any differences between risk factors for in-hospital mortality and dependence at discharge in patients with first-episode ischemic stroke in the middle cerebral artery (MCA) receiving intravenous thrombolysis (IVT) treatment. The study comprised a single-center cohort of patients admitted consecutively for first-episode MCA ischemic stroke. A logistic regression analysis was performed to determine the variables associated with in-hospital mortality and dependence at discharge. We included 169 patients (50.9% women) with a mean age of 64.1 ± 12.9 years and a median National Institute of Health Stroke Scale (NIHSS) score of 13 (range 3-26) at admission. Nineteen patients (11.2%) died as inpatients [the main cause of death was found to be infection (47.4%)]. The independent predictors for in-hospital mortality were: age (OR 1.09, 95% CI 1.03-1.15, p = 0.004) and NIHSS score (>17) at admission (OR 1.17, 95% CI 1.05-1.30, p = 0.004). Two other crude models used to analyze in-hospital mortality (age and symptoms-to-needle time, and age and symptomatic intracerebral hemorrhage) were significant. NIHSS score (>11) at admission (OR 1.29, 95% CI 1.17-1.42, p < 0.001) and large artery atherosclerosis stroke (OR 3.10, 95% CI 1.10-8.76, p = 0.031) were independently associated with dependence at discharge. Overall, the predictors for mortality and dependence in patients with first-episode MCA ischemic stroke treated with IVT were different. This knowledge might help to improve the management of this devastating disease.